If a political party wanted to tear America apart, weaken its position in the world, reduce our capacity to influence events, and encourage our adversaries, it would look exactly like what the Republican Party has done under Democratic presidents.

President Obama says Republicans are undermining his authority in negotiations with other countries. He gives several examples. One is the letter from 47 Republican senators advising Iran not to trust Obama’s promises in a nuclear deal. Another is Senate Majority Leader Mitch McConnell’s warning to foreign leaders that Obama’s domestic opponents won’t cooperate in any climate change plan he approves. The last straw was an allegation on Thursday from Sen. John McCain, the GOP’s 2008 presidential nominee, that U.S. Secretary of State John Kerry is lying about the terms of the Iran nuclear deal and that Americans should instead believe the contrary account given by Iran’s dictator.

Obama calls these developments a breach of precedent. Last week, he told New York Times columnist Tom Friedman: “I do worry that some traditional boundaries in how we think about foreign policy have been crossed.”

Traditional boundaries? Sorry, but those traditions died long ago. If you study Republican behavior over the past quarter-century, you’ll find that the image of conservative lawmakers standing resolutely for American strength and unity is a myth. Republicans support wars launched by Republican presidents. When Democratic presidents undertake wars or negotiations, Republicans generally attempt to sabotage them. In fact, Republicans often side with our enemies.

President Clinton faced one big war. In 1999, he sought to enlist the United States in NATO’s air campaign in Serbia. The campaign aimed to stop the ethnic cleansing of Muslims in Kosovo. When a resolution authorizing U.S. participation in the war came before the Senate, Democrats voted for it, 42 to 3. Republicans voted against it, 38 to 16. The resolution went through, but it failed a month later with a tie vote in the House. Democrats voted for the resolution, 181 to 25. Republicans voted against it, 187 to 31.

Four of the five Republican leaders in Congress—Senate Majority Leader Trent Lott, Senate Majority Whip Don Nickles, House Majority Leader Dick Armey, and House Majority Whip Tom DeLay—voted against the resolution. So did Rep. John Boehner, who had just completed his tenure as chairman of the House Republican Conference. DeLay also voted for a resolution declaring that the House “directs the President to remove United States Armed Forces from their positions in connection with the present operations against the Federal Republic of Yugoslavia.”

Republican leaders didn’t just try to block the president. They defended Serbian dictator Slobodan Milosevic. When Gen. Joseph Ralston, vice chairman of the Joint Chiefs of Staff, said Milosevic “had already started his campaign of killing” before NATO intervened, Nickles disagreed. “I would take a little issue with [what] Gen. Ralston said,” the senator retorted. “The number of killings prior to the bombing, I think, has been exaggerated.”

DeLay and Nickles blamed the ethnic cleansing on the United States and NATO. Nickles said NATO’s peace proposal to the Serbs—which Milosevic had rejected, leading to the war—had been “very arrogant.” Lott agreed. He accused the United States of not doing “enough in the diplomatic area” to appease Milosevic, and he urged Clinton to “give peace a chance.” Nickles dismissed NATO’s mission as “ludicrous.”

DeLay functioned as a propaganda minister for Milosevic, bucking up Serbian morale and belittling NATO’s efforts. “He’s stronger in Kosovo now than he was before the bombing,” DeLay said of Milosevic. “The Serbian people are rallying around him like never before. He’s much stronger with his allies.” When U.S. officials suggested that Milosevic was losing strength, DeLay dismissed this as disinformation from “the president’s spin machine.” DeLay concluded that “the bombing was a mistake” and that “this president ought to … admit it and come to some sort of negotiated end.”

The Republicans were wrong. NATO’s pressure forced Milosevic to capitulate, and the ethnic cleansing stopped. Then came the 2000 election, the attacks of Sept. 11, 2001, and the wars in Afghanistan and Iraq. Republicans didn’t just support these wars. They portrayed anyone who questioned them, even tactically, as a traitor. But in 2008, the GOP lost the White House, and its attitude toward presidential authority turned hostile again.

Republicans’ hostility focused not on Afghanistan or Iraq—the wars for which they couldn’t escape responsibility—but on Libya, which they could safely portray as Obama’s conflict. Throughout the 2011 Libya campaign and the 2012 election, they mocked Obama for “leading from behind” in Libya. Many Republicans said we should never have entered the war, since Libyan dictator Muammar Qaddafi hadn’t attacked the United States and posed no immediate threat to us.

Rep. Michele Bachmann, a presidential candidate and darling of the right, suggested that the U.S.-led NATO strikes in Libya had killed 10,000 to 30,000 innocent civilians. She cited, as her source for this claim, Qaddafi’s regime. In the 2012 presidential debates, former GOP House Speaker Newt Gingrich and other Republicans agreed with much of her criticism. “Two wars in Iraq and Afghanistan is a lot,” Gingrich argued in an NBC News interview. He accused Obama of going to war in Libya for the United Nations and the Arab League instead of “looking at American interests.” “We could get engaged by this standard in all sorts of places,” Gingrich objected. He concluded: “I would not have intervened.”

While the presidential candidates criticized the war, Republicans in Congress tried to stop it. Two months into the bombing campaign, House Speaker John Boehner sponsored and pushed through a resolution declaring that Obama had “failed to provide Congress with a compelling rationale based upon United States national security interests for current United States military activities regarding Libya.” The resolution forbade Obama from using U.S. ground forces and warned him that “Congress has the constitutional prerogative to withhold funding for any unauthorized use of the United States Armed Forces.” Democrats opposed the resolution, but Republicans passed it, voting 223 to 10 in favor.

Republican efforts to sabotage the U.S. war effort were so persistent and vigorous that Qaddafi sent a letter to members of Congress thanking them. The letter, issued a week after the House adopted Boehner’s resolution, told lawmakers: “We are counting on the United States Congress [for] its continued investigation of military activities of NATO and its allies.”

Qaddafi’s letter offended McCain. In a Senate floor speech, the senator chided his colleagues:

Last week, Qaddafi wrote a personal letter of thanks to the members of Congress who voted to censure the President and end our nation’s involvement in Libya. Republicans need to ask themselves whether they want to be part of a group who are earning the grateful thanks of a murderous tyrant for trying to limit an American president’s ability to force that tyrant to leave power.

McCain said that he and his Democratic partner, Sen. John Kerry, would rally the Senate to support the Libyan intervention. But four years later, McCain has turned against Kerry and Obama, joining fellow Republicans in trying to limit the president’s ability to deal with another tyrant. Last month, McCain and 46 other Republican senators—that’s 87 percent of the Senate Republican caucus—signed an “Open Letter to the Leaders of the Islamic Republic of Iran.” The letter warned Iran not to trust Obama or U.S. officials who were negotiating an agreement to restrict Iran’s nuclear program, since congressional Republicans could—and, implicitly, would—rescind any concessions made by the president.

It seemed unimaginable that McCain, a Vietnam War hero, trusted Iran’s theocratic rulers more than he trusted his own president. But on Thursday, McCain suggested precisely that. A conservative radio host, Hugh Hewitt, pointed out to McCain that Iran’s leaders were contradicting what Obama and Kerry (now the secretary of state) had said about the nuclear agreement. “Today, the supreme leader, Ayatollah Khamenei, said that the deal is no deal unless sanctions come off on Day One,” Hewitt told McCain. Hewitt noted that Iran’s defense minister was also ruling out inspections of Iran’s military centers, which were supposedly part of the deal. McCain, referring to Khamenei and the defense minister, replied:

You’ve got to give them a little sympathy in this respect, in that John Kerry must have known what was in [the deal], and yet chose to interpret it in another way. It’s probably in black and white that the ayatollah is probably right. John Kerry is delusional. ... You’re going to find out that they had never agreed to the things that John Kerry claimed that they had. So in a way, I can’t blame the ayatollah, because I don’t think they ever agreed to it, and I think John Kerry tried to come back and sell a bill of goods. … It reveals that a number of things about John Kerry’s negotiating capabilities and also his candor with the American people.
McCain was calling Kerry a liar based on the testimony of Iranian hard-liners, with whom McCain explicitly sympathized. And this episode was no fluke. A week before the Republican senators sent their letter to Iran, Boehner used his power as House speaker to bring Israel’s prime minister to Congress, against Obama’s wishes, to speak against the Iran deal. Meanwhile, McConnell launched a campaign to block Obama’s ability to negotiate a treaty on climate change. In a March 31 statement that echoed the tactics of the letter to Iran, McConnell advised foreign leaders not to trust U.S. commitments to reduce greenhouse gas emissions. “Considering that two-thirds of the U.S. federal government hasn’t even signed off on the Clean Power Plan and 13 states have already pledged to fight it,” he warned them, “our international partners should proceed with caution before entering into a binding, unattainable deal.”

Kosovo, Libya, Iran, Israel, climate change. These aren’t breaches of the norm. They are the norm. When Republicans leaders are presented with a conflict between a Democratic president and a foreign government, they tend to oppose the president—and often side with the foreign government.

As a liberal, I’m OK with that. The right to dissent is a core American value. It has kept this country free for more than two centuries. But when Republicans are in power, they vilify dissent. During the George W. Bush years, Vice President Dick Cheney and his henchmen ruthlessly attacked the patriotism of anyone who questioned—even on tactical grounds—their conduct of the Iraq war, surveillance, or “enhanced interrogations.”

Last week, just before McCain gave his interview to Hugh Hewitt, Cheney appeared on the same show. He said of Obama: “If you had somebody as president who wanted to take America down, who wanted to fundamentally weaken our position in the world and reduce our capacity to influence events, turn our back on our allies and encourage our adversaries, it would look exactly like what Barack Obama’s doing.” When Hewitt played back Cheney’s quote for McCain two days later, the senator agreed with it.

That’s a cold, clear, functional definition of treason. But it could be applied just as easily—and with a better fit—to Cheney, McCain, and their collaborators on the right. If a political party wanted to tear America apart, weaken its position in the world, reduce our capacity to influence events, and encourage our adversaries, it would look exactly like what the Republican Party has done under Democratic presidents. Make of that what you will.