Washington (CNN) White House chief economic adviser Larry Kudlow says President Donald Trump is trying to get China's attention by ramping up trade war rhetoric, but so far, Beijing has not wanted "to come round and talk in earnest."

"Look, we have had to go in and fire a shot across the bow. China's behavior, it's 20 years now, it's more than unfair trade practices. It's illegal trading practices," Kudlow said Sunday on CNN's "State of the Union," later emphasizing that "this is a process" and "no tariffs have been implemented yet."

Last Thursday, Trump ratcheting up the trade war rhetoric with China, saying he was asking US Trade Representative Robert Lighthizer to consider $100 billion in additional tariffs on the country's exports to the US.

The moves follow US tariffs that were imposed earlier this year on Chinese steel and aluminum, which also prompted retaliatory measures from China.

Kudlow, who joined the administration only days ago, said he would support the new tariffs if they were implemented.

"In this last round (of tariffs), President Trump asked Bob Lighthizer, our trade diplomat, to consider whether an additional round of tariffs would be useful, and part of that is because after we've made the first round, the Chinese response was unsatisfactory, to (say) the least," Kudlow said. "So the President is trying to get their attention again. The process may include tariffs. I can't rule that out. It may rest eventually on negotiations."

"Maybe China will want to come round and talk in earnest," Kudlow added. "So far it hasn't. I hope it does."

In a tweet Sunday morning, Trump wrote that Chinese "President Xi (Jinping) and I will always be friends, no matter what happens with our dispute on trade."

President Xi and I will always be friends, no matter what happens with our dispute on trade. China will take down its Trade Barriers because it is the right thing to do. Taxes will become Reciprocal & a deal will be made on Intellectual Property. Great future for both countries! — Donald J. Trump (@realDonaldTrump) April 8, 2018

"China will take down its Trade Barriers because it is the right thing to do. Taxes will become Reciprocal & a deal will be made on Intellectual Property. Great future for both countries!" he continued.

Peter Navarro, director of the White House Office of Trade and Manufacturing Policy, said in an interview on NBC's "Meet the Press" Sunday morning that though the tariff threats against China are serious, they're also a negotiating ploy.

"We're moving forward in a measured way with tariffs, with investment restrictions," he said. "What we want from China is very clear. We want fair and reciprocal trade. We want them to stop stealing our stuff. We want them to guard intellectual property, not take it from us."

On "State of the Union" Sunday morning, Republican Sen. Susan Collins, of Maine, said the administration needs a "more nuanced approach" to the issue, but gave the President credit for posing the treat of additional tariffs against China.

We need to get tough with China, but we need to do so in a way that we do not spark a trade war and retaliation that will end up with our European and Asian competitors getting business that otherwise would have come to American farmers and American manufacturers," Collins said.

Republican Sen. Lindsey Graham, of South Carolina, also credited Trump for taking action.

"To those who believe that China is cheating: What idea do you have better than Trump? He's the first guy to actually take them on, they have a weak economy compared to ours, the Chinese, they don't have Social Security or unemployment benefits," Graham said Sunday on ABC's "This Week." He added, "They need us more than we need them, and all I'm asking them to do, Martha, is to quit cheating us out of market share."