British Prime Minister David Cameron said it would be “unthinkable” for his country to fulfill a Russian order for warships -- as France is planning to do -- in light of the escalating conflict in Ukraine.

France and Russia signed a deal for two Mistral-class “amphibious assault ships” or “helicopter carriers” in 2011. Work started on them in 2013, but they’ve become a topic of debate as the crisis in Ukraine has escalated this year.

“Frankly in this country it would be unthinkable to fulfill an order like the one outstanding that the French have,” Cameron said to reporters. “But we need to put the pressure on with all our partners to say that we cannot go on doing business as usual with a country when it is behaving badly in this way.”

He also called Russian President Vladimir Putin’s allies “cronies and oligarchs.”

The ship orders are legal under current EU sanctions on Russia, but are threatened if the European Union decides to bump its sanctions to a third round. Cameron did not say France should put the ship orders on hold, but emphasized he thinks it is time to step up the EU sanctions in light of the downing of Malaysia Airlines Flight MH17 over separatist-held territory in Ukraine Thursday. All 298 passengers and crew members were killed.

Russian officials do not appear to be fazed by the threat of more sanctions, however. Russian Deputy Prime Minister Dmitry Rogozin said he doubted the deal would be canceled.

“This is billions of euros,” Rogozin told Reuters. “The French are very pragmatic. I doubt it [will be canceled].”

He went on to say a cancelation of the Mistral ships would hurt France more than it would hurt Russia.

When asked about the sale Friday, German Chancellor Angela Merkel only said Germany has put on hold the completion of a “shooting center” in Russia given the current situation. She also asked Russia to “acknowledge its responsibility,” for its role in the Ukrainian crisis.

Ukraine and NATO accuse Russia of supplying pro-Russia separatists with weapons, including the anti-aircraft rocket system that allegedly took down MH17.

The first of the two ships that are part of the $1.6 billion (1.2 billion euro) deal, the Vladivostok, is expected to be commissioned in November.