By Phil Stewart and Idrees Ali
WASHINGTON (Reuters) - President Joe Biden's nominee to become the Pentagon's top policy adviser faced relentless Republican criticism on Thursday over his support for the Iran nuclear deal, in a confirmation hearing that could foreshadow bigger fights over Biden's national security agenda.
Colin Kahl, who was a top aide to Biden during the Obama administration, reaffirmed his views on the 2015 Iran nuclear deal, strong defense ties with Israel and the U.S. military's so-called "triad" of nuclear missiles, submarines and bombers.
But Republicans including their most senior member on the Senate Armed Services Committee, Jim Inhofe, lambasted Kahl over his past remarks about Iran and social media posts that were sharply critical of Donald Trump's policies as president.
"How can you reassure this committee that your hyper-partisan advocacy would not drive Pentagon decisions?" asked the senator from Oklahoma.
Inhofe added that if he sounded a little upset, it was because "frankly, I am."
The Iran nuclear deal, aimed at preventing Tehran from acquiring nuclear weapons, was fiercely opposed by Republicans and some Democrats, and Trump withdrew from it in 2018. Biden wants to revive the deal, which was agreed by Tehran and six major powers.
Biden's bid for diplomacy has been overshadowed in recent weeks by rocket attacks by Iran-backed militia on U.S. forces in Iraq that have triggered concerns about escalation.
Kahl suggested he would favor strong responses to such attacks.
"When Iran takes actions against our own forces, we should defend ourselves and punch back," Kahl said.
'PROXY WAR' Tensions in Kahl's confirmation hearing echoed concerns raised on Wednesday, when a different Senate panel grilled Wendy Sherman over her nomination to be No. 2 official at the State Department. Sherman helped negotiate the 2015 Iran deal, and so is also likely to lose Republican votes.
During Thursday's hearing, Kahl defended his concerns about Trump's 2018 pullout from the Iran deal and the decision to pile pressure on Tehran, including round after round of economic sanctions. Kahl at the time worried it would encourage Iran to increase its provocations and accelerate its nuclear program.
"Both of those things have happened in the last three years. Iran is a lot closer to the fissile material required for a nuclear weapon than they were at the end of the Obama administration," Kahl said. "And we've seen more attacks."
Republican Senator Joni Ernst from Iowa said she would not support Kahl's nomination and that members of the U.S. military "deserve someone that will take a serious outlook to policy." Democratic Senator Tim Kaine said Kahl's hearing was being used by critics to re-litigate the 2015 agreement.
"I really believe that the controversy over your nomination is essentially a proxy war," Kaine said. "Republicans didn't like the Iran deal."
Republican Senator Tom Cotton said Kahl had warned on Twitter of the risk of conflict with Iran after the Trump administration killed top Iranian General Qassem Soleimani last year. He said Kahl had spent "the last four years warning about impending wars that never happened."
He also pointed to a tweet by Kahl describing Republicans as "the party of ethnic cleansing" after Trump abruptly ordered a Syria withdrawal in 2019 in a move that many said put at risk America's Kurdish allies.
Kahl apologized and said the last several years had been "pretty polarizing on social media."
"I'm sure there are times that I got swept up in that," he said.
(Reporting by Phil Stewart and Idrees Ali; Editing by Mary Milliken and Daniel Wallis)