Despite Russian President Vladimir Putin's recent order to reduce Moscow's military forces in Syria, two U.S. officials tell Fox News the opposite is taking place.

The officials said that Russia had deployed four additional attack aircraft to its coastal airbase in Syria earlier this week. One official said the jets had stopped in Iran to refuel before continuing on to Syria.

“[The Russians] say they are pulling out, but we have seen no evidence to support that. On the contrary, we have seen new things coming in,” said one official.

The four Russian Su-25 jets, known as Frogfoots by NATO -- arrived Monday, according to one official. The Su-25, similar to the U.S. Air Force’s A-10, is used for close air support. The Russian jet has reinforced armor siding to protect the pilots from ground fire.

One official also said the Russians have deployed additional Russian civilian contractors, as well as fighters from Chechnya, but would not provide any specific numbers.

The Russian military maintains roughly 36 fighter jets and helicopter gunships in Syria, a number unchanged in the last month, according to officials.

Putin ordered the military reduction in Syria in late December following the announcement of a new cease-fire agreement with Iran and Turkey. The United States was excluded from those talks.

On Friday, a top Russian military officer said Moscow’s only functional aircraft carrier, the Admiral Kuznetsov, would be returning home after deploying to the shores of Syria in mid-October.

Despite that announcement, U.S. officials say the Admiral Kuznetsov is currently conducting live-fire training exercises in the Mediterranean off the coast of Libya. Long-range bombers have also conducted strike missions in Syria from an airbase outside the city of Mozdok in southern Russia.

The Kuznetsov conducted dozens of airstrikes in Syria for more than two months. In some cases, jets from the ship flew ashore to Russia’s airbase in the port city of Latakia before conducting the missions. In addition, two jets from the aircraft carrier crashed during flight operations in the eastern Mediterranean in November and December.

In all, Russian aircraft made just 154 flights off the Kuznetsov in two months, a figure that U.S. officials believe speaks to the limited capability of the Russian forces.

“We do that in a few days [from our aircraft carriers],” the official told Fox News.

Russia began airstrikes in late September 2015. The next month, President Obama predicted Russian and Iranian forces would find themselves in a "quagmire" in Syria.