Turkish military forces crossed the border into Iraq on Friday last week in the name of "military exercises," "training local troops," and "jointly fighting against the Islamic State (IS)." Baghdad declared the move was a severe breach of its sovereignty and demanded that Ankara withdraw its forces immediately.

Turkey has only just downed a Russian jet for violating its airspace. If the latter really had crossed the line, it must have been only for a matter of seconds, and was more likely a mistake. In comparison, Ankara is obviously much more daring in terms of encroaching on Iraqi soil.

On the one hand, Turkey does not allow any warplane from other nations to fly across its territory, not even by mistake. It will shoot down whatever comes. On the other, it is publicly sending heavy equipment, including tanks and artillery, into another country. Its tough stance is indeed "impressive."

After having been stung by Turkey, Moscow has vowed to make Ankara regret its action. But so far, it has been acting with relative restraint.

The US attitude is complicated. Many believe that Washington has somehow acquiesced or indulged Turkey for shooting down the plane. But quite a few people tend to think that the incident happened because of Ankara's headstrong attitude and the US can no longer take this self-willed NATO ally under control. On the contrary, Washington is even forced to endorse it.

The reason probably lies in the decline of the US, as well as its falling determination and interests in its intervention in the Middle East.

However, Washington's attitude is perhaps the biggest external cause of Turkey's ill-disciplined behavior. Stabbing Russia in the back, as an unexpected way to upset Moscow, is generally in line with US interests.

Several US statements are worth pondering. Earlier, it said that the downing of the Russian jet is not connected with the US, yet Turkey has the right to protect its airspace. Now, it claims that Turkey's deployment in Iraq is not part of coalition efforts against the IS, but only a "Turkish-Iraqi arrangement." There were no harsh words at all. Imagine if Washington publicly criticized Turkey, would Ankara still be able to continue its wayward manner any longer?

Turkey had planned to purchase China's HQ-9 air defense system. Yet faced with public objections from NATO countries, including the US, it gave up on the deal in the end, which showed the real influence of the US on Turkey's decision-making.

Therefore, what Russia is confronting is not simply Turkey. The former must also consider the US backing behind Ankara. Russian President Vladimir Putin seems to be well aware of the essence of the problem. He appears to be looking for an angle and timing for revenge. A lot more is to happen in the Middle East.