Li Ru was certainly capable. Dong Zhuo had achieved what he had today largely thanks to him. He had poisoned the Young Emperor and Empress Dowager He, won over the court factions to stabilize the situation, and relocated the capital west to Chang'an to avoid the feudal lords' edge. When Wang Yun employed the Chain Stratagem, Li Ru had advised giving Diao Chan to Lü Bu, but Dong Zhuo had refused. If he had agreed, he might not have died so soon.
That did not necessarily mean he had seen through the Chain Stratagem. He simply understood Lü Bu's importance. Diao Chan was merely a beautiful woman; which mattered more was self-evident. Besides, he knew Diao Chan had been sent by Wang Yun. With his guard up, he offered advice, but Dong Zhuo would not listen, leaving him helpless.
Thus, he understood Dong Zhuo's implication perfectly.
He had already considered this during the two hundred and fifty li journey. That was why he did not hesitate now and spoke bluntly.
"Chancellor, Zhang Yang is surely only pretending to submit, but we cannot simply stand by. If that traitor Wang takes Wild Goose Gate, Chang'an will be in danger. If he takes Bing Province and moves down into Hedong, then advances into the Three Auxiliaries in one push, his troops are elite and battle-hardened, and he has great generals commanding them. Moreover, Wang Yan is even braver than Lü Bu. If he personally leads the army to attack, Chang'an will certainly be unable to withstand him. Yet our own situation is unstable as well. Chang'an needs a large army to suppress any unrest, so we cannot spare troops to stop Wang Yan."
After laying out the severity of the problem, Li Ru saw Dong Zhuo's impatience and moved on to the